At conception, gender is determined by chromosome characteristics - and it will be the male (or rather the male's sperm) that dictates whether the baby will be a boy or a girl. Prior to conception, the unfertilized egg carries an X chromosome while the sperm can carry either an X or a Y chromosome. The gender of the baby comes down to one simple event: - If the sperm carrying an X chromosome fertilizes the egg, a girl will be conceived. - If the sperm carrying a Y chromosome fertilizes the egg, a boy will be conceived. Studies indicate that the sperm with the X chromosome - or female chromosome - have a longer life span than the male sperm (with the Y chromosome). Yet the male sperm appear to have a higher motility. Sperm motility is measured in two ways: percentage of sperm exhibiting movement, and the quality of this movement, which is called the forward progression. Poor motility means the sperm have a difficult time swimming toward the egg. It is said that the sperm carrying the Y chromosome uses energy faster than the sperm carrying the X chromosome. The energy utilization is said to be due to the speed in which sperm swim. Supposedly, the Y sperm is speedy or contains less mitochondria whereas the X sperm is slower or carries more mitochondria. Mitochondria are the energy producing cellular components which are absolutely necessary for life. Sperm contain, and can only produce, so much fuel for their journey. Baby Gender Predictor method calculates probability of the sperm (with the X or the Y chromosome) ability to fertilize the egg at the time of conception. The calculations of the formula are based on the chemical properties of each of the male and female to best determine the sex of the baby due to the body chemistry throughout life.